Question 1

Which of the following best describes facilitated diffusion across the plasma membrane?

Accepted Answer

It uses specific carrier proteins to move molecules from high to low concentration without using ATP.

Question 2

The Na+/K+ pump is an example of which type of membrane transport?

Accepted Answer

Primary active transport

Question 3

Which equation best represents the stoichiometry of the Na+/K+ ATPase pump?

Accepted Answer

$$3\ \mathrm{Na}^+_{in} + 2\ \mathrm{K}^+_{out} + \mathrm{ATP} \rightarrow 3\ \mathrm{Na}^+_{out} + 2\ \mathrm{K}^+_{in} + \mathrm{ADP} + \mathrm{P_i}$$

Question 4

Which of the following is a key function of the Na+/K+ pump in neurons?

Accepted Answer

Maintains the ionic gradients necessary for action potentials

Question 5

A patient with multiple sclerosis is experiencing muscle weakness. What is the underlying cellular mechanism?

Accepted Answer

Autoimmune attack on oligodendrocytes in the CNS

Question 6

Which of the following statements about bulk transport is correct?

Accepted Answer

Endocytosis brings large molecules into the cell, while exocytosis releases large molecules out of the cell.

Question 7

Which neuroglial cell type is responsible for forming myelin sheaths in the peripheral nervous system (PNS)?

Accepted Answer

Schwann cells

Question 8

What is the main reason why axon regeneration is limited in the mature central nervous system (CNS)?

Accepted Answer

Production of Nogo proteins and glial scars by astrocytes

Question 9

Which of the following best describes the resting membrane potential of a neuron?

Accepted Answer

It is approximately $$-70\ \mathrm{mV}$$ due to the imbalance of charged ions and the activity of the Na+/K+ pump.

Question 10

Which of the following is NOT a characteristic of carrier-mediated transport?

Accepted Answer

Unlimited transport capacity regardless of molecule concentration

Question 11

A nerve is best defined as:

Accepted Answer

A cable-like collection of many axons in the PNS, which may be mixed (contain both sensory and motor fibers)

Question 12

Which of the following is TRUE regarding neurotrophic factors (neurotrophins)?

Accepted Answer

They promote the survival, differentiation, and growth of neurons.

Question 13

Which of the following best describes the function of sensory (afferent) neurons?

Accepted Answer

Transmit impulses from sensory receptors into the CNS

Question 14

Which of the following is a correct statement about the movement of ions during the action potential in a neuron?

Accepted Answer

Na+ ions move into the cell during depolarization.

Question 15

Which of the following is a function of astrocytes in the CNS?

Accepted Answer

Cover capillaries of the CNS and induce the blood-brain barrier

Question 16

A patient is diagnosed with Guillain-Barre syndrome. Which of the following is most likely affected?

Accepted Answer

Myelin sheaths of the PNS

Question 17

Which of the following best explains why facilitated diffusion exhibits saturation kinetics?

Accepted Answer

Carrier proteins can only transport a limited number of molecules at a time.

Question 18

Which of the following is TRUE about the difference between the CNS and PNS regarding myelin sheath production?

Accepted Answer

Schwann cells produce myelin in the PNS, oligodendrocytes in the CNS.

Question 19

Which of the following best describes the role of the Ca2+ pump in muscle cells?

Accepted Answer

It pumps Ca2+ from the cytoplasm into the extracellular fluid or ER, creating a strong concentration gradient.

Mechanisms of Transport Across Cell Membranes and Introduction to the Nervous System

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